Error free and reliable reception of communicated data is desirable features in a communication system. The communication system transmits data in chunks (“packets”) of encoded frames. Each of the encoded frames includes a preamble and a data section. The preamble may include information for allowing a receiver to synchronize the received frame and other information relating to the data being transmitted. Typically, the preamble includes samples of recurring data. These samples of recurring data are correlated to obtain correlation values at the receiver. The boundary of the preamble is identified by the obtained correlation values.
The samples in a preamble are chosen such that when recurring samples of data is correlated with a subsequent recurring samples of data, the value obtained by such correlation is expected to cross a threshold value. However, when a sample is correlated with a sample which is not the same (i.e. not recurring), then the value obtained by such correlation can fall sufficiently below the threshold value. In such a case, the boundary of the preamble is considered to be the sample for which the obtained correlation value is below the threshold for the first time. Since samples are recurring in nature but after the boundary it is assumed that the recurring nature of the samples diminished and a sharp fall in the obtained correlation value is observed.
The systems operating according to the above description may work fine for white Gaussian noise under mild delay spread channel conditions. However, at high delay spread channel the correlation based threshold detection performance deteriorates as the spread of the channel can affect the threshold detection.